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fix(TLS/ConnectionHandler): Improve handling of TLS session resumption without SNI by sending an unrecognized_name alert instead of immediately terminating the connection. This change adds a grace period for the client to retry the handshake with proper SNI and cleans up the connection if no valid response is received.

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Philipp Kunz 2025-03-16 13:19:37 +00:00
parent 6c1efc1dc0
commit 9dd402054d
3 changed files with 97 additions and 23 deletions
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8
changelog.md
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@ -1,5 +1,13 @@
# Changelog
## 2025-03-16 - 4.1.5 - fix(TLS/ConnectionHandler)
Improve handling of TLS session resumption without SNI by sending an 'unrecognized_name' alert instead of immediately terminating the connection. This change adds a grace period for the client to retry the handshake with proper SNI and cleans up the connection if no valid response is received.
- Send a TLS warning (unrecognized_name alert, code 112) when a ClientHello is received without SNI and session tickets are disallowed.
- Utilize socket cork/uncork to ensure the alert is sent as a single packet.
- Add a 5-second alert timeout and a subsequent 30-second grace period to allow clients to initiate a new handshake with SNI.
- Clean up and terminate the connection if no valid SNI is provided after the grace period, logging appropriate termination reasons.
## 2025-03-15 - 4.1.4 - fix(ConnectionHandler)
Refactor ConnectionHandler code formatting for improved readability and consistency in log messages and whitespace handling

2
ts/00_commitinfo_data.ts
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@ -3,6 +3,6 @@
*/
export const commitinfo = {
name: '@push.rocks/smartproxy',
version: '4.1.4',
version: '4.1.5',
description: 'A powerful proxy package that effectively handles high traffic, with features such as SSL/TLS support, port proxying, WebSocket handling, dynamic routing with authentication options, and automatic ACME certificate management.'
}

106
ts/classes.pp.connectionhandler.ts
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@ -560,9 +560,18 @@ export class ConnectionHandler {
// Always block ClientHello without SNI when allowSessionTicket is false
console.log(
`[${connectionId}] No SNI detected in ClientHello and allowSessionTicket=false. ` +
`Terminating connection to force new TLS handshake with SNI.`
`Sending unrecognized_name alert to encourage client to retry with SNI.`
);
// Set the termination reason first to avoid races
if (record.incomingTerminationReason === null) {
record.incomingTerminationReason = 'session_ticket_blocked_no_sni';
this.connectionManager.incrementTerminationStat(
'incoming',
'session_ticket_blocked_no_sni'
);
}
// Send a proper TLS alert before ending the connection
// Using "unrecognized_name" (112) alert which is a warning level alert (1)
// that encourages clients to retry with proper SNI
@ -577,38 +586,95 @@ export class ConnectionHandler {
]);
try {
socket.write(alertData, () => {
// Only close the socket after we're sure the alert was sent
// Give the alert time to be processed by the client
setTimeout(() => {
// Make sure the alert is sent as a single packet
socket.cork();
socket.write(alertData);
socket.uncork();
// Set a longer timeout to allow the client to properly handle the alert
// The client might respond by closing the connection or initiating a new handshake
const alertTimeout = setTimeout(() => {
if (!socket.destroyed) {
console.log(`[${connectionId}] Client didn't respond to TLS alert, closing connection gracefully.`);
// Gracefully end the connection
socket.end();
// Ensure complete cleanup happens a bit later
// Only destroy after a delay if it's still hanging
setTimeout(() => {
if (!socket.destroyed) {
console.log(`[${connectionId}] Forcibly closing connection that didn't terminate properly.`);
socket.destroy();
}
this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni');
}, 2000);
}
}, 5000); // Give the client 5 seconds to respond to our alert
// Don't let this timeout keep the process alive
if (alertTimeout.unref) {
alertTimeout.unref();
}
// Handle a proper close from the client
socket.once('close', () => {
clearTimeout(alertTimeout);
console.log(`[${connectionId}] Client closed connection after receiving TLS alert.`);
this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni_client_closed');
});
// Also handle if the client sends more data (possibly a new handshake with SNI)
socket.once('data', (newChunk) => {
clearTimeout(alertTimeout);
console.log(`[${connectionId}] Client sent new data after TLS alert, checking for SNI...`);
// This would normally be handled by our renegotiation handler,
// but since we're in a special case, we'll check for SNI again
if (this.tlsManager.isTlsHandshake(newChunk) && this.tlsManager.isClientHello(newChunk)) {
const newServerName = this.tlsManager.extractSNI(newChunk, connInfo);
if (newServerName) {
console.log(`[${connectionId}] Client provided SNI in new handshake: ${newServerName}`);
// Update the record
record.incomingTerminationReason = null;
// Remove termination stats increment
// Note: This is a little hacky as we don't have a proper way to decrement stats
// Process the new handshake with SNI
record.lockedDomain = newServerName;
setupConnection(newServerName, newChunk);
return;
} else {
console.log(`[${connectionId}] Client sent new handshake but still without SNI, closing connection.`);
socket.end();
setTimeout(() => {
if (!socket.destroyed) {
socket.destroy();
}
this.connectionManager.cleanupConnection(
record,
'session_ticket_blocked_no_sni'
);
}, 100);
}, 100);
this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni_retry_failed');
}, 500);
}
} else {
console.log(`[${connectionId}] Client sent non-handshake data after TLS alert, closing connection.`);
socket.end();
setTimeout(() => {
if (!socket.destroyed) {
socket.destroy();
}
this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_invalid_response');
}, 500);
}
});
} catch (err) {
// If we can't send the alert, fall back to immediate termination
console.log(`[${connectionId}] Error sending TLS alert: ${err.message}`);
socket.end();
this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni');
}
if (record.incomingTerminationReason === null) {
record.incomingTerminationReason = 'session_ticket_blocked_no_sni';
this.connectionManager.incrementTerminationStat(
'incoming',
'session_ticket_blocked_no_sni'
);
}
return;
}
}